Aerial system employed in wireless signaling



1 618,299 Feb. 9 s. B SMITH ET AL AERIAL SYSTEM EMPLOYED IN wmsmss smxmuue Filed March 8, 1921 I Fig.1

wuewtoz W $171 MM maze sIDNEYBERT A sMiTii, oi? noeltoag-Aim qEoBeEm/rA JrtreE VTRIGHT,;OF- CHESTER- FIELD, ENGLAND ASSIGNORS To THE RAbI'o'coRroRAT'IoN or AMERICA, or NEW YORK, N. Y., A CORPORATION OF DELAWARE.

Asian; SYSTEM EMPLOYED IN WIRELESS SIGNALING.

"2.3.: fs-.1 '.'L H. \"i I, Y' I. ,i Application filed March 8, 1921, Serial No. 450,630, and in Great Britain December 24, 1919.

v (GRANTED UNDER Tits rittiSibNst-F THE Adi: or iiA'Rcir 1921,41 STAT. It, 1313;)

This inv'eii tioii, relates to aerial sysits ohject'is to provide a1i improved system in which the well kii' oiv'n heart sha ped polar diag'rani can be readily obtained for ascertainirig the bearing of a station or for ehmifiii sfli 'bii is or. o her P 1 PQ$$ ,A'ccording' to this invention We employ a differential transformer the secondary of which is shunted by a variable condenser by means of which the systemcan'be tuned. One primary is connected eithento a pair of loop aerials through a tightly coupled radiogoniometer or to a rotatingloop aerial; and the other primai'y is connected to earth and to middle points of the bases of the two loops or to the iniddle point of. thebase of the rotating loop. The necessary phase and amplitude adjustment is provided by the insertion of a resistance in series with one of the primary windings. I I I I The only tuningrequired is effected by means of the condenser'and in practice phases reniainunaltered over Wide ranges of Wavelengths. I I p I,

Figure 1 of the accompanyingdrawing is a diagrammatic representation of' a simple arrangement in accordance with our invention.

Fig; Zis a vectordiagram 'illustratin gthe probable vector relations of currents and electromotive forces existing in Fig. 1

Fig, 3 is a diagrammaticrepresentation illustrating a further improvement over Fig. 4 is a-vector diagram of the probable vector relations existing in F igh 3. Fig; 5 illustrates the heart shaped polar diagrain of the system. p M H ef eri'ing' particularly to Fig ltlie leads A BC and D from two frame or'loop aeri als at right'angles areconiiected in'the'usua] manner to the field coils'of E F F and F of a radiogonioineter, of which the tightly coupled search coil S is" connected to the primary P of a differential transih rn eri of which the secondary Winding J is shunted y e d u ab pon e 's lK y i h he complete circuitcan tuned to the desired Wavelength. A. vertical aerial obtained by connexion, to the mid points of thegifa:

diogoniometer fields is connected through a" pedanc'e of the remainder ofthe' circuit the "1 currentresulting from this E. M; E'willbe approiziinately in phase with it, and can' be representedv by the vector IV. The vector EF. representsthe 1 1M; F; induced in the loop, laggingdegrees behind EV,"and 7 since the impedance of the loop aerial circuit is niaiiily inductive the current in this" 5 circuit lag 90 degrees .behindEF and can be represented by the vectorIF; It is 7 clear that IF' and 1V arei18O degrees apart in phase and that-they Will add or subtract according to. the positionof the search coil S. -Adjustinent of the current amplitude-in the. verticalwire can be obtained by thead- 'justine i1t otthe resistance R provided that the-initial-E. M. F. (EV) is large enough,

as is usually the case in practice. It should be noticedthat the circuit possesses'theim 'portant advantage that providing the initial connexions areright a reversal of sense by incorrect adjustment of the circuits isimpossible, the only eiiect produced being an 1 impure I minimum.

Figure 3 shows an alternative arrange ment possessing a greater selectivity and capable of giving apurerininiinum than i that given bythe cireuits'of Flgure 1.' In;

this case a loosely coupled jigger is employed. The primary l and the balancing coil B are connected to the search coil or the radiogonioineter and tuned by means of the variable condenser K,,'the jiggersecondary J being loosely coupled to P and tuned by the variable condenser K lVhen the correct value of R and a suitable adjustment of coupling between B and T are ob tained the heart-shaped polar diagram results. "We prefer to couple T to the coil B rather than to P in order to 'make certain that in the direction of minimum signals on the polar diagram an incoming signal shall produce no current in the circuit K, P B. \Vere T coupled to P (and consequently to J) the best adjustment would be obtained when the currents in P and T were of such intensities and in'such directions as to produce zero magnetic held in J. The presence of any current in the circuit K,

P B may cause an undesirable shift in phase 7 of the currents in the loop aerials and so renderit diflicult to obtain a perfectly pure minimum.

In order to obtain the purest minimum we find it best to arrange the inductance of the coil T that the wave length of the vertical aerial circuit is a. little shorter than the wave length it is desired to receive. The

. reason for thiswill be evident from a closer consideration of the vector diagram of the E. M. Es and currents in the circuits. In Figure t let EF represent the E. M. F. induced in the frame aerial by the incoming wave. Now owing to the fact that this aerial possesses a certain resistance the currents in it will not lag exactly 90 degrees behind EF, but will have a phase angle slightly less than 90 degrees as shown by the vector IF; EV represents the E. Id. F.

induced by the: wave in the vertical aerial circuit. Again owing to the fact thatthis circuit possesses inductive and capacity reactance, the current can never be exactly in phase with EV (except in the particular case of resonance). Consequently the vector IV may occupy either the position IV or In, depending upon whether inductive or capacity reactance predominates. The best balance will obviously be obtained when this current vector occupies the position TV, when capacity reactance predominates in the vertical aerial circuit, i. e. when the tune of this circuitis a little shorter than the wave length to be received.

Referring to Figure 5, which is a repro-Q duction of the heart-shaped polar diagram of the system, it can be shown that the maximum slope of the polar curve occurs at the points X and Y. At these points the ordinate OX is equal to OY, consequently it the search coil is adjusted to such a position that no change of signal strength occurs on reversing the Connexions to it, e. upon rotatin the polar diagram through 180 degrees, this position will represent the direction of the incoming signal. Also the determination will have been made in a region on the polar curve where a given change in angle of the radius makes the greatest change of dili erence in the two signal strengths.

A simple form of stand-by can also be obtained in which the system receives ap proximately equally in all directions hori Zontally by short 'circuiting the resistance R; in which case ordinary vertical aerial reception results, superimposed upon the relatively weak directional effect of the frame acrials.

, W hat we claim is:

' 1. A directional aerial system comprising an aperiodic loop grounded through a re sistance of such value that the antenna voltage and current in the ground connection are substantially in phase.

2. A directional aerial system comprising a pair of aperiodic crossed loops, a ground connection for said loops and a resistance in the ground connection of such value that the antenna voltage and current in the ground connection are substantially in phase.

3. A directional aerial system comprising an aperiodic loop, an inductance in said loop, a ground connection to' a mid point of said inductance, and a resistance in the ground connection of such value that the antenna voltage and current in the ground connection are substantially in phase.

a. A directional aerial system comprising an aperiodic loop grounded through'a resistance of such value. that the antenna voltage and current in the ground connection are substantially in phase, and means for combining the .loop and ground currents.

5. A directional aerial system comprising a pair of stationary crossed loops and coupling coils therein, a ground connection to a mid point'of said coils, a resistance in the ground connection of such value that the antenna voltage and current in the ground connection are substantially in phase, a rotatable coil for coupling with the loop coils, and

tially in phase, and means for combining currents of the loop and ground connection.

7. In a wireless direction finder systen' comprising a receiver, the combination of an aperiodic loop aerial, a ground connection from the mid-point of said loop, means for adjusting currents in said loopand ground a ei-5 QQnne tien to sub antia eq ali y and-op posite phase in saidreceiver for waves from a certain direction and comprising a resistar se-in said ground lead of deastsuliicient value to insure that antenna voltage and current, in said ground connection are substantially in phase, and meansQfor: combining currents from saidfiloop and said ground connection. 7 V

8. In a Wireless direction finder system, comprising a receiver, the combination of an aperiodic loop aerial, a ground connection from the mid-point of said loop, means for adjusting currents in said loop and ground connection to substantial equality and opposite phase in said receiver for Waves from a certain direction and comprising a resistance in said ground lead of at least sufiicient value to insure that antenna voltage and current in said ground connection are substantially in phase and a circuit associated with said loop and said ground connections.

9. In a Wireless aerial system, the combination of an aperiodic loop aerial, a ground connection for the loop adapted to provide a vertical aerial, a circuit associated with each of said aerials and a resistance in one of the aerials of such value that the antenna voltage'and current in said aerial are substantially in phase.

10. In a Wireless aerial system, the combination of an aperiodic loop aerial, a ground connection for the loop adapted to provide a vertical aerial, a circuit associated with a portion of th aerial carrying currents due to loop and vertical aerial reception, and a resistance in the vertical aerial of such value that the antenna voltage and current in said aerial are substantially in phase.

11. In a wireless aerial system, the combination of an aperiodic loop aerial, a coil deriving currents from the loop aerial, a resistance, a second coil deriving currents from the vertical aerial connected to the loop and to earth through the resistance, said resistance being of sufiicient value to insure that antenna. voltage and current in said ground connection are substantially in phase, a circuit for combining the currents derived from said coils and tuning means in said circuit.

12. In a wireless aerial system, the combination of an aperiodic loop aerial, an inductance coil therein, a resistance, a connection to the mid point of said coil and to earth through said resistance to secure a vertical aerial, said resistance being of such value as to insure that antenna voltage and current in said ground connection are substantially in phase, a coupling coil in the vertical aerial and a circuit associated with each of said coils.

13. In a wireless aerial system, the combination of an aperiodic loop aerial, a coil derivin currents from the loop aerial, a connection from said loop to earth adapted to pro ide a vert ca aeria ista ce i one ofQthe aerials andof such valuethat antenna voltage and current in said yertical aer al. ar s bst ial y in p as s coil associated Wit/1'1 "the vertical .-aer a1, Circuit associ w h eac o s d coil and niegm an sai rcuit. j

.ln Wire es aerial system, th bination of an aperiodic loop aerial, acoil therein, a resistance, a coil connected from the mid point of said first mentioned coil to earth through said resistance, said resistance being of such value that the antenna voltage andcurrent in said connection are substantially in phase, adapted to provide a vertical aerial, a third coil associated with the first mentioned coil, a fourth coil associated With the second mentioned coil, a circuit for combining the currents from the third and fourth mentioned coils and tuning means in said circuit.

15. In a Wireless aerial system, the combination of an aperiodic loop aerial, a coil deriving currents from the loop aerial, a connection from said loop to earth adapted to provide a vertical aerial, said vertical aerial being tuned to a shorter Wave length than the signal to be received, a resisto ance 111 one of the aerials, aco1l associated With the Vertical aerial, a circuit associated with each of said (30115 and means for vary mg the tuning of said circuit.

16. In a Wireless aerial system, the combi nation of an aperiodic loop aerial, a ground connection for the loop aerial adapted to form a vertical aerial, means for combining currents from said aerials and a resistance in the ground connection of such value that the antennavoltage and current in said connection are substantially in phase.

17 In a Wireless aerial system, the combination of a loop, a differential transformer, one primary of Which is connected to the loop, the other primary being connected to earth and to the frame in such a manner as to form an aerial with uniform radiation and a resistance in series with one of the primaries.

18. In a wireless aerial system, the combination of a loop, a differential transform er, one primary of which is connected to the loop, the other primary being connected to earth and to the loop in such a manner as to form an aerial with uniform radiation, a resistance in series with one of the primaries and tuning means connected to the secondary of the differential transformer.

19. In a. Wireless aerial system thecombination of an aperiodic loop, a differential transformer, one primary of which is'connected to the loop,pthe other primary being connected to earth and to the loop in such a manner as to form an aerial with uniform radiation and a resistance in series with one of the primaries.

20. In a Wireless aerial svstem the combination of an aperiodic 10010, a differential transformer; one primary of which is connected to, the loop, the other primary being connected. to earth and to'the loop in such a manner as to form an aerial with uniform radiation, a resistance in series with one ofthe prlmanes and 'tumng'iineans connested-to the secondary of the differential transformer.

In testimonyethat we claim the foregoing as our invention, we have; signedour names this 14th day of February, 1921.

SIDNEY BEETRAM SMITH, -GEORGE MAURICE WRIGHT. 

